Field of the Invention
The Invention relates to oligophenol cyanates of the general formula
[Axe2x80x94]n[Bxe2x80x94Axe2x80x94]xB[xe2x80x94A]mxe2x80x83xe2x80x83(I).
In this formula, A is in each case a group of the formula 
and B is in each case a group of the formula 
R1, R2 and R3 on each group A independently of the others are in each case hydrogen or a bond to a group B with the proviso that each group A has either one or two bonds to B.
Both R4 and R4xe2x80x2, and R5 and R5xe2x80x2, on each group B independently of the others, are in each case either together a direct bond or, in any desired order, are hydrogen and a bond to a group A with the proviso that each group B has either one or two bonds to A. The indices m and n are 0 or 1 and x is an integer from 0 to 10 with the proviso that at least one of the numbers m, n and x is other than 0 and m and n are not both at the same time 1.
The Invention also relates in particular to mixtures of such compounds with one another and/or with those compounds of the formula I in which m and n deviate from the above definitions by both, being 1.
Saturated oligophenol cyanates of general formula I in which m and n deviate from the compounds of the present invention by both being 1 are known, for example, from EP-A-0 147 548 and are marketed by the Dow Chemical Co. under the designation XU71787. These compounds do not have any olefinic double bonds and are therefore able to polymerize only by cyclotrimerization of the cyanate groups or by reaction with functional groups of other compounds. The cyclotrimerization requires the presence of catalysts and/or high temperatures. In contrast it is often desirable to achieve partial curing or crosslinking by means, for example, of irradiation at room temperature. In addition, these known compounds have a relatively high viscosity, which is unfavourable for some applications.
The object of the present invention was therefore to provide oligophenol cyanates which have a low viscosity and which without further additives can be (partially) polymerized or crosslinked at room temperature by means, for example of radiation-induced free-radical reactions.
In accordance with the invention this object is achieved by the unsaturated oligophenol cyanates of the formula I of the invention. The molecule of these compounds has at least one olefinic double bond (R4xe2x80x94R4xe2x80x2 and/or R5xe2x80x94R5xe2x80x2 according to the formula I) which permits free-radical addition polymerization. 
The degree of polymerization, x, lies preferably between 0 and 5 and, with particular preference, between 0 and 3.
The unsaturated oligophenol cyanates of the invention can be prepared by reacting an oligophenol of the general formula:
[Axe2x80x2xe2x80x94]n[Bxe2x80x94Axe2x80x2xe2x80x94]xB[xe2x80x94Axe2x80x2]mxe2x80x83xe2x80x83II
in which Axe2x80x2 is a group of the formula: 
and B, R1, R2, R3, R4, R4xe2x80x2, R5, R5xe2x80x2, m, n and x are as defined above and elsewhere herein, is reacted with cyanogen chloride in the presence of a tertiary amine. Oligophenols of formula II are obtainable from Borden Chemical Inc. under the designations ESD-X1 to -X5, ESD-472C and ESD-473C. The, compounds concerned here are condensation products of dicyclopentadiene (dimeric cyclopentadiene) and phenol, which are present as a mixture of isomeric and/or homologous compounds and also contain fractions of saturated compounds where m=n=1.